Archives-February 2022

Tunnels represent a key part of the world transportation system playing a fundamental role both in people and freight transportation, especially in developed countries. Around the world, most major cities and metropolitan areas have metro systems accounting for hundreds of kilometers of underground tunnels and network systems. This study presents the pressure losses in ventilation systems of a long circular tunnel using for a metro purpose length of 700m, and diameter 6.6m, K.M.R.C., Kolkata has been vividly studied and presented in this dissertation. The tunnel which is being driven in the soft soil by using a tunnel boring machine has already developed up to a length of 700m and till the excavation is going on to continue. Auxiliary ventilation is adopted to ventilate the tunnel with the help of an axial-flow fan connected to a duct of approximately 680m in length. The various ventilation related parameters, viz. air quantity, pressure and temperature of the air in various locations inside the tunnel have been studied. In addition, we emphasize the pressure losses in tunnels in various locations i.e., to consider as bend taking place has been calculated. In the Kolkata metro, there is an earth pressure balance TBM is used. EPB excavation provides continuous support to the tunnel face by balancing the earth pressure against the forward pressure of the machine, and the advancement rate is 15 meters every day. In addition, the pressure losses in various tunnel configurations have been computed from the empirical relations as well as computational fluid dynamics (CFD) simulations. The aim of this project work is to correlate the values of pressure losses of analytical results and the computational simulation results with the help of using CFD software and conclude the difference of graph plotted to assess the adequacy of the tunnel and suggest a few measures to improve the ventilation inside the tunnel for building a cordial environment and enhancing the tunneling operation. This study suggests that pressure losses in field study and CFD simulation are approximately the same.

Tuberculosis and HIV co-infection is a major public health problem worldwide. Tuberculosis in HIV-infected patients presents clinical and paraclinical atypicalities making the diagnosis of this pathology difficult.We report in this manuscript the observation of a patient with multifocal tuberculosis revealing HIV infection.

The present study was the suitability and quality of groundwater for irrigation and domestic purposes in premonsoon and postmonsoon. Groundwater samples were collected in seventy locations in both the seasons in the year of 2016. Various physicochemical tests were carried out and WQI was calculated based on pH, TDS, Ec, TH, Ca, Mg, Na, K, Cl, So4, HCo3and F. The comparison between the premonsoon and postmonsoon reveals that very good range 27% and 6%, and good to permissible range in premonsoon 73% and in postmonsoon 94% of the water samples were fit for drinking.

A semi-classical Boltzmann transport model is developed to observe photon-assisted dynamics of induced carriers in the graphene nanoribbons. When the nanoribbons are subject to a multi-frequency Alternating Current (ac) field and superimposed on by static Direct Current (dc) field, an unusual non-linear response of the system shows up at a rather strong drive force. The non-linearity in the photo-current allows for up-conversion necessary for low-frequency oscillators. Regions of positive differential conductivity are observed paving way for graphene to be operated as a small signal amplifier for Terahertz (THz) applications. The fractional photon-assisted phenomenon is also observed when the stark factor r > 1 and the ratio of the n-th harmonic to stark factor takes on half-integer values.

The cervical cancer is the most common gynecological malignancy in the world, its incidence is greatly reduced thanks to screening methods. The Pelvic organ prolapse increases with age, obesity, and parity. The Cervical cancer complicating uterine procidence is a rare event and requires a multidisciplinary approach

The majority of households in the town halls of Agbangnizoun and Za-Kpota do not have access to drinking water due to the non-existence of drinking water supply. Consequently, the communities of these two town halls use surface waters, traditional wells and cisterns to satisfy their daily needs without any prior treatment. This work was undertaken to assess the physico-chemical quality of these waters. Thus, over two successive years, twelve (12) rivers, eighteen (18) wells, twenty (20) cisterns and two (02) boreholes (witness samples) were sampled in the Districts of the two town halls. The physical parameters such as the pH, the temperature, the turbidity, the rate of dissolved solids (TDS) and the conductivity were measured in situ with a mobile multi-parameter device of the brand HANNA HI 9829 while the colour, the suspended matters (SM), the ammonium, nitrate, nitrite, phosphate and sulphate ions are measured in the laboratory by colourimetric method. The data collected were recorded in Excel and then treated with software R. The Student-Newman Keuls test with the significance level of 5% shows that surface waters are more polluted whereas well waters are highly mineralized. The waters consumed by the populations of Agbangnizoun and Za-kpota town halls do not respect drinking water standards.

In this study, the aim is the treatment of phosphogypsum and phosphate sample collected in the senegalese chemical industries and actions of management for the valorization of the phosphogypsum. The treatment of phosphogypsum and phosphate show that naturally impurities are present in the samples and this chemical analysis of the treated of the phosphogypsum established improvement of the quality of it. The values observed of MgO, SO3, P2O5, in the phosphogypsum were 24.811%, 57.054% and 1.763% respectively and 35.166%, 0.741%, 53.225% in the sample phosphate if the device is calibrated with standards type mining. The toxic elements found in our study were Mercury, Lead, Cadmium, and Arsenic if we calibrated by standards of mining type, thier activity is low than limit detection of the device for the gypsum, while in sample phosphate, we find a very low quantity of Arsenic and Cadmium equal to 08,860 ppm and 48,380 ppm respectively, when we calibrated with soil type standards, the concentrations of Mercury, Lead and Cadmium are not detectable, while for Arsenic the value was 09,550 ppm for Phosphogypsum and 03,040 ppm for Phosphate. The major phases Alite (C3S), Belite (C2S), Aluminatetricalcic (C3A), and Tetra-calcium aluminoferrite (C4AF), and control ratios Lime Saturation Factor (LSF), Aluminium/Iron ratio (AR), and Silica ratio (SR) were measured. These experimental results shown that the C3S, C2S, C3A, C4AF, LSF, AR and SR contents fulfilled the requirement of the Jordan Standards and European Standards. The acidity of samples, was an unfavourable parameter for geotechnical and mechanical properties due to the impurities, The data show that the evolution of densities as a function of compaction energies was not analogous to that of sand, mainly because of the fragility of phosphogypsum crystals as the compaction energy increases, the crystals break and the fragments fill the inter-granular voids.

Seismic wave propagation through acoustic medium allows us to understand response through a fluid saturated medium. This interaction has been described by the acoustic wave equation. In this work, the acoustic wave equation was written in coupled form and was discretized using the staggered grid finite difference (SGFD) method, which provides improved accuracy and efficiency of the numerical modeling and are naturally centered at the same point in space and time. To truncate artificial reflections from our computational boundary, we have applied the perfectly matched layer (PML) absorbing boundary condition. Our results show seismic wave propagating through a homogeneous medium and the effect of PML was clearly observed.

In technology adoption in the educational field and school system, teacher training is imperative to increase success. In Guyana, indigenous Amerindian preservice teachers were found to lag in successful adoption. The study findings indicated that this demographic may need to prioritize acquiring the skills and overcome the technological barriers to better prepare learners beyond the classroom. Although internet access facilitates adoption, indigenous Amerindians in Guyana develop technology literacy skills and access educational resources, indigenous pre-service teachers have a low rate of technology adoption in the classroom. The purpose of this qualitative study is to discover the perceptions of indigenous Amerindian preservice teachers about the adoption of digital technology in the classroom. Rogers’s diffusion of innovation theory and David and Venkatesh technology of acceptance model constituted the underlying theoretical grounding, which served to understand indigenous Amerindian preservice teachers’ perceptions about the use of digital technology, perceived barriers, and the coping and adopting mechanism throughout their pedagogical practices. Ten indigenous Amerindian preservice teachers participated in this qualitative study. Semistructured, interviews were the primary data collection tool. Open coding was used to generate themes and analyze emergent coding. The findings showed that the rate of adoption of digital technology could accelerate if (a) training is strategic, (b) reduction of institutional barriers, and (c) professional practices are aligned for educational growth. This study may contribute knowledge to the advancement specific to the field of digital technology and pedagogical practices. The findings may have positive implications for the community at large in that professional development centers can improve skills that provide flexible learning for IAPT to integrate digital technology beyond the classroom. and serve as a catalyst to promote growth by capacity building.

Table of contents for the month of February 2022